Abstract: Theoretical analysis, numerical simulation and field observation were used to define the rational width of coal pillar in Wangjialing coal mine. Based on different theories, a larger range of coal pillar width were obtained, and this proved that different theories had a strong dependence on the relevant parameters. Based on the theoretical analysis, FLAC 3D software was used for assessing different sizes of coal pillars. When the coal pillar width was over 20m, the stress concentration, the plastic zone development and deformation around the tunnel could be improved, which was good for the stability of the roadway. Based on theoretical analysis, numerical simulation and field observation, it was suggested that the existing 25m clear width coal pillar with a surplus capacity could guarantee the stability of the roadway. On the condition that the basic geological conditions in the next work face remain unchanged, the coal pillar width is proposed to 20m by strengthening supports and monitoring, and it is good for improving the availability of resources.

Key words: hick coal seam, optimization of coal pillar width, numerical simulation, theoretical analysis, massive methane